quick Timing chain question

[bhuff30]

If you are swapping cams without taking the front cover off, can the timing chain slip on the crank if you leave them slack? If there isn't enough clearance for the chain to slip a tooth when the cover is still on, it is a piece of cake... just mark the chain and cam sprocket and put it back together like that, right?

 

[wmburns]

timing chain may slip if no tension

The timing chains can easily jump if the tension is relaxed and one side is pulled. Ford makes a special tool to wedge between the crank shaft gear and timing chain. It is a specially shaped piece of plastic on a long handle. The tool is inserted through the top of the cover and wedged in place to hold the chains in place.

I have heard others use a buddy to hold the chains while doing work.

It might be a good idea to set #1 cylinder at TDC before starting work.

OBTW; if all of the roller followers have been removed, there is no danger of PTV contact.

 

[bhuff30]

Alright, thanks. I'll definately put the crank at 0* when I do the work. I am just looking for ways to confirm I don't jump timing. Of course, there is a good chance I'll end up pulling the cover anyway...

It is so easy on the 2.3. At TDC, just run a string from the aux shaft to the cam and all the marks should be along the string. On the 4.6, if the crank is at TDC, will the marks on the cam sprocket be inline with the crank?

 

[wmburns]

First, I am going to assume this a SOHC engine.

If you are lucky, there will be a "marker" chain link that is visible. You may have to rotate the engine by hand several times in order to get it to line up.

With the #1 cyl on TDC, try to get the marked link on 11 O'clock on the right side and 12 O'clock on the left. From this postion, the engine is set up just like the installation procedure.

Do not rotate the crank shaft. Do not rotate the cams. Take a picture just in case. Maybe even take some measurments from fixed reference points (measure from the timing mark to the edge of the cover for example).

If the chain does slip, then you could restore timing by getting the cam marks at 11 O'clock on the right and 12 O'clock on the left. #1 at TDC. Of course with the cover on, you will have no way to verify that the marked link is at 6 O'clock. But the slipped chain won't hurt anything as long as the cams are still timed in relationship to the crank.

 

[bhuff30]

Thanks, that makes sense with the other information I was reading. Yes, this is for a 2v PI cam swap. I'm just trying to be extra cautious and know exactly what I'm doing before I begin. I like my valves in the shape they are in now.

Here is what I'll do: Remove the valve covers and the roller rockers on one side. Set the crank to TDC with the marks on the chain and cam sprocket showing (crank around 10:30, TDC should be marked on the cover). Then, I'll make a mark on the front cover where a streight edge goes from the sprocket mark, thru the center of the cam bolt and to the cover. This must absolutely line up when I'm done, long as the crank is still at TDC. If the chain didn't slip, then the chain marks will line up too. I'll have someone hold the sproket and chain for me when I remove the cams. I honestly don't trust the "it looks like 11 o'clock to me". I would prefer the marks. After I know the cam is timed correctly, I can put the rockers back on and do the other side.

Thanks again.

First, I am going to assume this a SOHC engine.

If you are lucky, there will be a "marker" chain link that is visible. You may have to rotate the engine by hand several times in order to get it to line up.

With the #1 cyl on TDC, try to get the marked link on 11 O'clock on the right side and 12 O'clock on the left. From this postion, the engine is set up just like the installation procedure.

Do not rotate the crank shaft. Do not rotate the cams. Take a picture just in case. Maybe even take some measurments from reference fixed points (measure from the timing mark to the edge of the cover for example).

If the chain does slip, then you could restore timing by getting the cam marks at 11 O'clock on the right and 12 O'clock on the left. Of course with the cover on, you will have no way to verify that the marked link is at 6 O'clock. But the slipped chain won't hurt anything as long as the cams are still timed in relationship to the crank.